The researchers found that the highest levels of African ancestry in those that self-report as “black” are found in individuals that currently live or were born in the southern US, especially in South Carolina and Georgia. It was found that those living in the Northeast, Midwest, Pacific Northwest, and California had lower levels of African DNA. It was also estimated that about 22% of Americans of African ancestry have some level of American Indian ancestry as well, with those having the highest level of American Indian ancestry living in New York state and Oklahoma. Those that self-reported as “black” that had the highest levels of European ancestry were found to be primarily from West Virginia and Washington state. For those that self-reported as “white”, but have greater than 2% African ancestry, most are from South Carolina and Louisiana.
Interestingly, when studying the sex bias through comparing estimates of the X-chromosome, it was estimated that of the European ancestors of black Americans, about 5% were European females and 19% were European males. I often find in discussion, read in articles, etc. that a general assumption is that European ancestry found in black Americans is derived from men, through forced relationships with black female slaves. However, in my own research I have found this is often not the case. More so in the early years of the colonization of America, in the 1700s, it was not uncommon for white women to have relationships with black men, who were at the time primarily non-chattel indentured servants rather than slaves. One might expect that there would be a greater disparity between European ancestry in black Americans having been inherited from men rather than women. But according to this study, based upon the X-chromosome (which is inherited by both men and women), the variance is fairly small. It was also found that for black Americans that have American Indian ancestors, about 4 times as many of their American Indian ancestors were female than male.
The researchers also concluded, contrary to the “Rule of Hypodescent” (the “One-Drop Rule”), that individuals tend to self-identify with whatever the majority of their ancestry is.
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